Specifics of soil temperature under winter wheat canopy

Abstract

The aim of this study was to evaluate the course of soil temperature under
the winter wheat canopy and to determine relationships between soil temperature, air
temperature and partly soil moisture. In addition, the aim was to describe the dependence
by means of regression equations usable for phytopathological prediction models, crop
development, and yield models. The measurement of soil temperatures was performed at
the experimental field station Žabčice (Europe, the Czech Republic, South Moravia). The
soil in the first experimental plot is Gleyic Fluvisol with 49–58% of the content particles
measuring < 0.01 mm, in the second experimental plot, the soil is Haplic Chernozem with
31–32% of the content particles measuring < 0.01 mm. The course of soil temperature and
its specifics were determined under winter wheat canopy during the main growth season
in the course of three years. Automatic soil temperature sensors were positioned at three
depths (0.05, 0.10 and 0.20 m under soil surface), air temperature sensor in 0.05 m above
soil surface. Results of the correlation analysis showed that the best interrelationships
between these two variables were achieved after a 3-hour delay for the soil temperature at
0.05 m, 5-hour delay for 0.10 m, and 8-hour delay for 0.20 m. After the time correction,
the determination coefficient reached values from 0.75 to 0.89 for the depth of 0.05 m,
0.61 to 0.82 for the depth of 0.10 m, and 0.33 to 0.70 for the depth of 0.20 m. When
using multiple regression with quadratic spacing (modeling hourly soil temperature based
on the hourly near surface air temperature and hourly soil moisture in the 0.10–0.40 m
profile), the difference between the measured and the model soil temperatures at 0.05 m
was −2.16 to 2.37 °C.